This has always been a theory in my head, but may as well voice it to get feedback. The open differential model years ('08 and '09) seem to be a few ticks quicker in the quarter mile compared to the 2010+ models based on Internet research. Perhaps the rear locks up differently on launch. There are several reviews from the typical sources such as MotorTrend, Edmunds, and Car and Driver that show the newer models being a few tenths slower through the trap. Slower to the point of it being noteworthy in their reviews. I would provide sources but I'm lazy and it's easy enough to look up. They blame it on a green engine but I'm not so sure. It's something to think about. Maybe the limited slip models require a rethink on launching technique. Maybe it's just a slightly slower car, all things being equal.

I also now think there is something to this. After searching through our racing thread at the top, it seems all of those with the great 60 foots are 08 and 09 models (include cayman, toothdoc, dv8),